Quentin Blake may have won more honors than any living picture-book artist. Nearly 30 years ago he received the Kate Greenaway Medal – England’s equivalent of the Caldecott – for Mister Magnolia, one of more than 250 books he has illustrated. He has since been named Britain’s first Children’s Laureate, had an art school named after him and won the Hans Christian Andersen Award for Illustration, the highest international award in his field. He also helped to bring worldwide fame to Roald Dahl, whose writing is controversial enough that it might have fared less well without Blake’s brilliant art.

So is Blake easing up now that he’s in his 70s? Or allowing himself to ride the coattails of his own successes? Not on the evidence of his illustrations for Michael Rosen’s Sad Book, which are among his finest. His art and the text by Rosen – best known for his collaboration Helen Oxenbury on an acclaimed version of We’re Going on a Bear Hunt – make this one of the great picture books of the decade and more than worthy of its Boston Globe–Horn Book Honor award.

Perhaps nobody but Rosen and Blake could have sold publishers on its difficult subject — Rosen’s sorrow about the losses of aging, including the death of his “mum” and his son, Eddie. American publishers hate topics like this, as do many child psychologists, because they have the potential to upset children and can’t be easily resolved in 32 pages. Suggest that a child might die before a parent? And that there may always be “a sad place” inside an adult because of the loss? This heresy to some experts — even when many children have watched reports of kidnappings or school shootings over and over on television. So publishers churn out sappy and “psychologically correct” books on safe topics like, “I feel sad because my friend doesn’t want to play with me any more” without acknowledging that sadness – in children and adults – can have much deeper causes.

Michael Rosen’s Sad Book is different. Rosen writes in the first person and with real feeling about his sorrow about his mother and son, Eddie: “Maybe it’s because things now aren’t like they were a few years ago. Like my family. It’s not the same as it was a few years ago. So what happens is that there’s a sad place inside me because things aren’t the same.” He talks about things he does to feel better — “like trying to do one thing every day that means I have a good time” — but doesn’t suggest that they are a cure-all. He might see a packed train: “And then I remember things. My mum in the rain. Eddie walking along the street, laughing and laughing and laughing.”

Blake’s illustrations add infinitely to the power of this deeply moving story, carrying it far beyond the words. Blake has a tremendous gift for subtle visual metaphors. In some pictures he uses black and gray monotones that show how loss can seem to drain the color from life. In two early pictures, Rosen looks spectral, haunted by his son’s death. In a later one, he sits on a bed in a room so barren it looks like a cell, suggesting that he sometimes feels isolated or even imprisoned by grief. And the pictures of Eddie convey so much joy that you ache for the father who lost him.

But – great as this book is – it isn’t for every child. In order to appreciate this book, children need to have a strong grasp of the finality of death, which many don’t have until about the age of 6. So the publisher’s suggested “4-to-8-year-old” age range is – as the experts say – “developmentally” off the mark, because its themes are too mature for most 4-year-olds. The book is best for about ages 7 and up. It’s also a book adults may want to give only to a child they know well.

With those cautions, Michael Rosen’s Sad Book is the rare picture book that doesn’t pay lip service to grief but makes you feel it. It gives children far more credit than most for being able to have deep feelings and sense when others have them. If Blake has illustrated more than 250 books, as his biographies say, this one makes you hope he as 250 more left in him.

Best line/picture: Most of the illustrations are pure genius, none more so than the last. The wordless final spread shows Rosen sitting alone, writing at a table that holds a candle and a framed picture. Like the other illustrations, this one is simple but symbolically rich. The candle suggests the glow of memory while the pen or pencil in Rosen’s hand evokes the redemptive and sometimes therapeutic value of art.

Worst line/picture: None. But the somewhat flat title Michael Rosen’s Sad Book doesn’t do justice to the eloquence of this book or Blake’s contributions to it.